I think you are wrong there. According to the New 52, Bruce is only like a few months older than Clark.
If you look at their childhood, Bruce was a normal rich boy until the age of 8 when his parents got killed, and he started his mental and physical training at the age of 14. So basically he was a normal guy till he was 14. He was 29 when he officially became Batman.
On the other hand, Clark already started developing his powers as soon as he got exposed to the sun, he was lifting trucks before he could walk steady.... He had all of his powers by the time he was in high school. At the age of 18 he decided to be a superhero and fight crime, and at the age of 25 he became Superman.
So to sum it up, lets say they fight at age 35. Batman would have 15 years of training and 6 years of practice fighting crime. And Superman would have 18 years of "playing" with his powers and 17 years of practice vs criminals. So no, I would not consider Superman a developing kid.